Tropoelastin (A protein found in the aortas of copper deficient swine) has been partially sequenced in this laboratory. Mos of these sequence studies have been accomplished by a study of its tryptic peptides. It is the aim of this laboratory to complete the sequence determination of this protein in the next five years. It will be accomplished by the following methods: a) a blockage of lysine residues allowing us to cleave the protein at arginine by the use of trypsin, b) thrombin digestion which cleaves the protein ar arg-ala and arg-gly bonds, c) digestion with collagenase type A which appears to give six peptide fragments, d) utilization of the Staph aureus protease of Drapeau et al. By a combination of several of these mechanisms of cleavage we feel we can obtain sufficient overlap information to characterize the protein completely. Full characterization up till this time has not been possible because of problems with microheterogeneity in our protein preparations caused by enzymatic degradation during the isolation procedure. This we have overcome by employing enzyme inhibitors such ad DFP during purification. The studies for the coming five years will also involve a study of the fluorescence of elastin and elastin peptides aimed at determining the cause of this unique phenomenon and utilizing it as a tool to study maturation, a study of in vitro desmosine production in cell culture with the aim of obtaining a cell line which produces a significant amount of the crosslinks, and an evaluation of elastin and tropoelastin from a number of species to evaluate similarities and dissimilarities in primary structure to the procine aortic material which we are characterizing.